`2a^2 - 2 - 4ab + 2b^2`
`= a^2 + a^2 - 2 - 2ab - 2ab + b^2 + b^2`
`= (a^2 - 2ab + b^2) + (a^2 - 2ab + b^2)`
`= (a - b)^2 + (a - b)^2 - 2`
`2x^2 - 12x + 18 + 2xy - 6y`
`= 2(x^2 - 6x + 9 + xy - 3y)`
`= 2[(x^2 - 6x + 9) + (xy - 3y)]`
`= 2(x - 3)(x - 3^2)`